| OCR Text |
Show 612 MR. W. L. SCLATER O N A N E W JERBOA. [Nov. 4, Behind the large anterior palatine foramina there are found, between the posterior molars, a large pair of posterior palatine foramina, which are only represented by very minute passages in the other Jerboas. The very large size of the bulla? in Euchoreutes causes them nearly to meet in the median line, where, as in all other Jerboas, there is a considerable interval between the two bulla? in the region of the basioccipital. In the lower jaw of Alactaga there is between the condyle and the angle an outwardly and backwardly projecting thick process of bone, which is very conspicuous in all the species of that genus that I have been able to examine ; this process is quite unrepresented in Euchoreutes. The dentition of Euchoreutes is similar to that of Alactaga, and consists of one premolar and three molars above, and three molars below ; the crowns of the molars, however, are much shorter, and the cusps much longer and sharper than those of other Jerboas. The incisors, as in Alactaga, are not grooved. The following measurements are in inches and decimals :- Total length from snout to base of tail 3*25 Tail to end of vertebra? 5-85 „ with hairs , 6'40 Length of ears from vertex 1*55 Distance from snout to ear (in extracted skull) .. 1*20 Fore limb from elbow-joint to end of toes 1 '10 Tarsus to end of 1st digit 1'15 2nd „ 1-65 „ 3rd „ 170 ,, 4th „ 1-65 .. 5th „ MO Total length of skull M5 Breadth of zygoma '50 „ at brain-case '53 „ at interorbital constriction *30 Length of nasals '45 Anterior palatine foramen '20 Length of molars and premolars '20 „ lower jaw from the condyle to the incisors '70 Habitat. The two specimens of Euchoreutes naso were procured by the Hon. Charles Ellis, during his journey through Eastern or Chinese Turkestan, and presented to the Indian Museum. They were probably obtained by him in the sandy plains round the city of Yarkand, but no exact locality is attached to them. The new genus Euchoreutes belongs essentially to the Dipodince as defined by Alston (P. Z. S. 1876, p. 89), of which subfamily it will form a fourth genus. I subjoin a table of the principal characters of the four genera. |
